1. Field of the Invention
The present invention relates to a camera of the single lens reflex type using a semi-transparent mirror as a pop-up mirror, and specifically relates to a digital camera of the single lens reflex type provided with a pop-up semi-transparent mirror having a function of blocking stray light entering the camera through the finder during photography.
2. Description of the Related Art
Although there are various types of cameras, in digital cameras of the lens shutter type, an image to be photographed is not viewed through the photographic optical system but rather is viewed through a finder optical system provided separately. In this type of digital camera, when the magnification ratio is increased and near range imaging is performed, a problem arises insofar as the range of the image viewed during image sensing and the image actually sensed is shifted due to parallax. In order to eliminate this disadvantage the single lens reflex type digital camera has been proposed.
Although there are various types of single lens reflex cameras, such cameras typically use a totally reflective mirror as a pop-up mirror. In this type of single lens reflex digital camera, the totally reflective mirror is disposed at a position (finder viewing position) inclined 45° relative to the optical path while the photographer is looking through the finder. Since the light passing through the taking lens cannot reach the image sensing element when the totally reflective mirror is set at the finder viewing position, disadvantages arise insofar as autofocusing by the image sensing element, exposure confirmation, and white balance adjustment cannot be performed.
Digital cameras of the single lens reflex type using a semi-transparent mirror substituted for the aforesaid totally transparent mirror have been proposed. In this type of single lens reflex digital camera, light passing through the taking lens is normally split to the image sensing element and the finder, but in this case further disadvantages arise insofar as only one half the amount of light reaches the image sensing element, thus darkening the image, and limiting the photographic conditions.
A digital camera of the single lens reflex type using a semi-transparent mirror as a pop-up mirror is proposed to eliminate these disadvantages. A camera of this type is shown in FIG. 1. In FIG. 1, light passing through a taking lens 1 is split in two so as to form light used for image formation on a solid state image sensing element 3, and light used for image viewing passing through an eyepiece finder 9. The photographer is able to view the image to be sensed through the finder, and make various adjustments and settings based on the image data collected by the solid state image sensing element 3. Thereafter, when actually taking the photograph, a semi-transparent mirror 2 springs upward in the arrow a direction to direct the entirety of the light from the taking lens 1 to the solid state image sensing element 3 for use in image sensing, as shown in FIG. 2. As a result, the amount of light used is approximately double that when a prism is used, making it difficult to restrict the photographic conditions, and allowing photography under a broader range of photographic conditions.
Digital cameras of the single lens reflex type using a semi-transparent mirror as a pop-up mirror have the further disadvantages listed below.
As shown in FIG. 2, during daytime photography, the light from the sun S enters the interior of the camera as harmful external light, i.e., stray light, from the finder eyepiece 9, as indicated by the arrow b. During photography, since the semi-transparent mirror 2 is set at the up position, after the stray light is transmitted through the semi-transparent mirror 2, this light is reflected by the interior wall surface of the camera body 20 and attains the solid state image sensing element 3 Accordingly, this stray light adversely affects the photographed image as ghost and flare, and is the cause of exposure error. Particularly during photography using the self timer, or during photography while viewing a liquid crystal display 19 provided on the back of the camera body, the stray light phenomenon becomes marked because the face of the photographer is separated from the finder eyepiece 9 such that the face of the photographer no longer covers the eyepiece 9.
When the semi-transparent mirror 2 is lifted during photography, the light passing through the taking lens 1 is directed only to the image sensing element 3, and is not directed to the finder, such that as a natural result the photographer cannot see the image through the finder when the photograph is taken. That is, the photographer cannot directly confirm through the finder whether or not there was an error in the image when the photograph is taken.